Stendra, from Vivus Inc., is in the same drug class as the four oral ED drugs now on the U.S. market: Cialis, Levitra, Staxyn (an orally dissolving version of Levitra), and Viagra. An estimated 30 million U.S. men have ED, according to the FDA.

"This approval expands the available treatment options to men experiencing erectile dysfunction, and enables patients, in consultation with their doctor, to choose the most appropriate treatment for their needs," Victoria Kusiak, MD, deputy director of the Office of Drug Evaluation III in the FDA's Center for Drug Evaluation and Research, states in a news release.

In some participants in clinical trials, the drug was effective in as little as 15 minutes. Some men in clinical trials reported improved erections more than six hours after taking the drug.

In clinical trials, 77% of men with general ED were able to get erections after taking Stendra, compared to 54% of men taking an inactive placebo pill. Among men with diabetes-related ED, 63% were able to get erections after taking the drug, compared to 42% of men taking placebo.

Stendra resulted in successful intercourse for 57% of men with general ED (vs. 27% of men taking placebo) and for 40% of men with diabetes-related ED (vs. 20% of men taking placebo).

The main side effects of avanafil are similar to those of its sister drugs: headache, flushing, stuffy nose, and back pain. Rarely, an erection lasting for four or more hours may occur, which would need immediate medical attention. Other side effects occurring rarely include color vision changes, sudden loss of vision, and sudden loss of hearing. If sudden loss of vision or hearing occurs, it is recommended to call a doctor immediately.

Men who take nitrate medications should not take Stendra because the combination of these two medications can lead to a sudden drop in blood pressure.